This grant is divided into three parts. (1) An experimental laboratory study utilizing an ex vivo, perfused canine pancreas preparation will further explore the basic pathogenetic mechanisms of triglyceride and drug-induced acute pancreatitis. (2) An experimental laboratory study utilizing an ex vivo, ventilated, perfused canine pulmonary lobe will study mechanisms involved in respiratory failure in acute pancreatitis. Possible roles for phospholipase A and triglycerides will be studied. This part will also involve collecting serum phospholipase A, free fatty acid, and tryglyceride levels from patients presenting with acute pancreatitis, and correlating them with blood gases and clinical respiratory status. (3) The third part of this grant will study the efficacy of intravenous Cimetidine in the treatment of acute pancreatitis, in a prospective, randomized clinical trial.